<?php
class Foo
{
    static $variable = 'static property';
    static function Variable()
    {
        echo 'Method Variable called';
    }
}
//需要变量的场合
echo Foo::$variable . "<br>"; // This prints 'static property'. It does need a $variable in this scope.
$variable = "Variable";

//调用函数的场合
Foo::$variable();  // This calls $foo->Variable() reading $variable in this scope.

?>